1. Field of the Invention
The present invention relates to a headlamp or an auxiliary headlamp for a vehicle and, more specifically, to a projector type headlamp which employs an elliptic reflection surface such as a composite elliptic surface.
2. Background Art
FIG. 7 shows the configuration of a conventional projector type headlamp 90. The projector type headlamp 90 has a reflecting mirror 92 having a complex elliptic surface and a first focus where a light source 91 such as a tungsten halogen lamp is provided, and a shade 93 near a second focus of the reflecting mirror 92 is provided. In front of the shade 93, there is provided a projection lens 94 whose focus is in the vicinity of the shade 93.
The light source 91, the reflecting mirror 92 and the projection lens 94 are arranged such that their centers are aligned with an optical center line (an optical axis) Z of the projector type headlamp 90 and the shade 93 is arranged such that an upper end thereof is substantially aligned with the optical center line Z.
In the thus formed projector type headlamp 90, since light converges as an elliptic pencil of rays having such a cross section which is wider in a horizontal direction at the second focus by the reflecting mirror 92, a portion of light unnecessary from a viewpoint of light distribution characteristics is shaded by the shade 93 to shape the pencil of rays and the shaped pencil of rays is projected in a radiation direction by the projection lens 94.
FIG. 8 shows an example of light distribution characteristics QDP obtained by the projector type headlamp 90 configured as described above in which the cross section of the pencil of rays whose lower half portion is shaded by the shade 93 is inverted upside down by the projection lens 94 and projected. At this point, to facilitate the confirmation of a road shoulder side, a road illuminating portion DPL which rises at an angle of 15.degree. to the left from the center of the light distribution characteristics is provided by the shape of the shade 93 when this headlamp 90 is for passage on the left.
The light distribution characteristics QDP show the actual measurement values of the projector type headlamp 90 which uses a 55W tungsten halogen lamp as the currently used light source 91 and the total quantity of light for generating the light distribution characteristics QDP is substantially 485 lumen and the maximum luminous intensity is 21,800 candela.
However, in the conventional projector type headlamp 90 described above, firstly, since a light quantity distribution in the direction of the cross section of the pencil of rays is determined by the characteristics of the reflecting mirror 92 and a relatively uniform brightness distribution is obtained from an elliptic reflecting surface such as the above-described complex elliptic surface, illuminance in a front direction of an automobile becomes not so high due to light distribution characteristics, thereby lowering the remote visibility.
Secondly, in this projector type headlamp 90, since a light emitting portion which can be seen from the outside when the headlamp lights up is only the projection lens 94, the portion has an extremely small area, and light radiated from the projection lens 94 has strong directivity, the visibility of the outside at night deteriorates. Further, thirdly, since an opening portion is only the projection lens 94 having a small area, external light hardly enters therein, and the projection lens 94 appears black and looks like a hole during daytime when the headlamp does not light up with the result that it mars the appearance of the headlamp. Solutions to these problems are awaited.